Automotive vehicles have used gravity feed for fuel in the early stages of the industry and the next phase beyond this was a diaphragm pump in which the diaphragm was mechanically pulsed by a lever actuated by a cam actuated by the engine itself. Also, electric pumps have been used with the pumping action provided by a solenoid armature reciprocating in a solenoid winding in response to electrical contacts in a circuit responsive to the motion of the armature.
In every case there is a problem of matching the fuel supply to the demand of the engine under all conditions of operation, whether it be idling, full open throttle at high speed, or open throttle under load such as climbing a hill or moving through sand or snow where the load causes a reduced speed even with open throttle.
It is also important to have a fuel pump which will have a reliable output under all conditions of ambient temperature in winter and summer.
It is an object of the present invention to provide a constant speed rotary electric pump which can yet respond to fuel demand by the operation of a unique relief or by-pass valve at the rotary pump inlet. A further object is a rotary pump design which has a steady, even output flow with minimal surging in the output so the engine fuel mixing device can perform its function unaffected by a surging fuel supply.
Another object is a pump design which is compact and of a size to be easily mounted in a safe area in an automotive vehicle. It can be mounted in or out of the fuel tank.
Another object is to provide a unit wherein the pump assembly automatically aligns itself to the motor shaft, thus preventing friction or binding due to misalignment.
Other objects include providing a pump relief system which can provide a substantially constant pump outlet pressure even though the outlet flow may vary from the maximum desired flow to a minimum flow.
The pump incorporates a simple pressure regulator valve in conjunction with pulse absorption devices to provide a smooth flow of fuel. The pressure relief valve is designed for an initial lift-off in response to pump pressure and automatically expose additional area to the pressure to steady the by-pass and avoid an erratic or jerky "hunting" for the desired pressure. Attention is directed to U.S. Pat. No. 3,415,195, to Catterson, dated Dec. 10, 1968, and U.S. Pat. No. 3,470,824, to O'Connor, dated Oct. 10, 1969, where a magnetic relief valve plate is utilized in connection with a rotary fuel pump.
A further object is the provision of a retainer shell which holds the respective parts together under resilient compression in a sealed relationship.
A further object of the invention is the provision of a pump shaft bearing at the outlet end of the pump assembly and a pump housing retainer shoulder at the pump end cooperating with a spherical annular surface to permit pump shaft alignment without binding forces on the shaft.
A further object is the provision of a rotary pump housing with an outlet end plate and bearing press-fitted therein to a proper relationship with the pump rotor, thus avoiding expensive machining operation to obtain a proper fit. A resiliently biased relief plate with annular pockets for exposure to pump outlet pressure is provided at the inlet end of the pump in the form of a thin metal disc with annular pressure ridges disposed in a common plane.